Diversity and Connectivity: Population Genetic Structure of the seagrass within the Banc d'Arguin

hasliza mohdnasir

Seagrass population resilience may be influenced by the level of population connectivity and by their reproductive mode, whether it is mainly clonal propagation or sexual reproduction by seeds with distinct genotypes. This study aimed to understand the reproductive and dispersal ecology of the seagrasses of the Banc d'Arguin. These questions were addressed using hypervariable genetic markers (microsatellites) for all three species of seagrasses within the Banc d'Arguin. Results showed that population persistence of all three species of seagrass inhabiting the Banc d’Arguin is highly mediated by successful seed recruitment as shown by the high proportion of distinct genotypes in all populations. This is unexpected for populations occurring at the edge of their distribution ranges, where marginal habitat conditions are hypothesized to restrict successful sexual recruitment, leaving populations more reliant on clonal propagation.  Results also show that all sites of all seagrass species sampled in the Banc appear to be mostly highly connected, forming a single population, which could be a consequence of the strong internal seawater currents within the Banc d'Arguin. These conditions confer higher population resilience and are thus very favourable for the conservation of the seagrass meadows of the Banc d'Arguin.